Interleukin-12 as an adjuvant for cancer immunotherapy

Interleukin-12 (IL-12) is a cytokine whose main effect is to drive Th-cell differentiation throughout a T helper type 1 cell type of response, thus inducing interferon gamma (IFNgamma) and favoring a switch from Ig to IgG2a. These properties make IL-12 a candidate adjuvant for vaccination against cancer and infection disease. Enthusiasm was generated in many animal studies where IL-12 was given either systemically or locally. The experience of some toxicity in humans has hampered its further development into clinical applications, which, however, are still possible if restricted to local administration. Gene transfer seems to be the preferred approach to obtain this local release of cytokine. Here we review the applications of IL-12 as adjuvant.